If you have a garden plot that you are ‘done with’ for the year and want to let it rest during the winter, but also want to do something with it that will put it in better shape come next spring, consider planting a “cover crop”.
Cover crops are helpful for various reasons, including building the soil, suppressing weeds, controlling soil erosion, increase organic matter in the soil, and recycle soil nutrients. Cover crops are primarily used to “rest” or leave a garden area open during non-production times.
As such, we most often planted in the fall, however, summer cover crops can be equally effective and can provide the same benefits as a fall cover crop.
Also called “green manure”, these are never planted with any intention of being harvested. Rather, they contribute to soil improvement in the place where they are grown. Most gardens benefit from the use of cover crops when not planted, instead of leaving the garden fallow (unplanted).
Let’s look at a couple of example of what could be planted now to carry your site thru winter and be ready for spring gardening.
Two really simple winter cover crops that I’ll push are rye grain and Crimson clover. These can be used alone or together to get the best out of each.
Rye grain (not to be confused with ryegrass) works in two ways. It works on all the areas mentioned earlier and it serves as a trap-crop for root-knot nematodes. You’ll want to plant 2-4 lbs per 1,000 square feet.
Be sure to ask for Elbon rye at the local feed store for best nematode control. Elbon rye is unique in that it will allow the nematodes into its roots and will be infected. But, it also traps the nematodes so that they cannot escape to infest other plants later in the season. It ‘traps’ them!
The second plant that I’ll push is Crimson clover. Crimson clover is the beautiful, dark red (crimson?) flower that you’ll see on roadsides and in some pastures around this region in the spring. Purchase and plant ½ lb per 1,000 square feet.
Now our intent is to use that clover for its nitrogen-fixing ability that all legumes can do. Incorporating legumes into the soil adds nitrogen much better than any other plant.
Crucial to this cover crop procedure is to kill the plants at least three weeks before you plan on planting in that area of the garden. So, if you are planning on planting potatoes in mid-February, then you’ll mow down and then till in your rye and/or clover about mid-January so that the cover crop will have time to decompose and provide all the benefits to the potato crop that is being planted.
Now for the neighboring row that is planned for tomatoes. You’d be wise to wait until all chance of frost is past before planting tomatoes as well as many other spring garden vegetables. So, you would mow-down and till-in your cover crop in early March.
That last section of your garden, saved for summer heat tolerant purple hull peas and okra, may very well see the clover blooms and grain seed heads before you mow them down, till them in three to four weeks before planting your summer vegetables.
It should be noted that for maximum benefit, a cover crop should be terminated (killed) while in the flowering stage. At this point, the crop will return the greatest amount of biomass and nutrients to the soil. But with onions, potatoes, and many other vegetables that we do not want to wait until June to plant, we terminate them earlier to suit our needs.
Another option is to mow down the cover crop and then leave the material on the surface as a mulch. This works best if you are looking to do a no-till kind of garden program. The root biomass in the soil will still provide a valuable volume of organic matter.
The value of organic matter cannot be understated. Soil building is a continual process in the garden. And it is important to understand that organic matter is continually decomposing and cannot be built up permanently in the soil. Just because you purchased a load of compost years ago and tilled it in, does not mean that you are done. Soil must be replenished with nutrients and organic matter regularly for the best results.
Other suggestions for a winter cover crop are winter wheat, oats, barley, Daikon radish, mustard, annual ryegrass, rapeseed, turnips, and several other clovers.
If you want to try a summer cover crop, consider Sorghum-Sudangrass, Buckwheat, cowpeas (think poor quality Purplehull peas), and others.